The result is likely a surprise to no one: Trillions of cigarette butts are littered worldwide each year, making them the most common type of litter. And that litter has consequences.

Sidewalks littered with cigarette butts detract from the appeal of their surrounding neighborhoods, making them appear unsightly and neglected, much less places where people want to gather and patronize local businesses. Inevitably, cleaning up many of those cigarette butts falls to the residents and business owners who take pride in their neighborhoods.

The next rainstorm often sweeps away the cigarette butts that aren’t picked up, guiding them to storm drains, then waterways. There, the heavy metals present in cigarettes and the plastics that make up their filters start to break down, contaminate water bodies and endanger marine life. One 2011 study found that it took just two cigarette butts per liter of water to wipe out more than 90 percent of freshwater fathead minnows and saltwater topsmelt.

Those are 300,000 cigarette butts that won’t find their way into waterways. Instead, they’ll be transformed into compost, plastic park benches, shipping pallets and railroad ties. That’s because when a cigarette “buttler” fills up, it’s sent to New Jersey-based TerraCycle, a firm that specializes in transforming otherwise non-recyclable waste into saleable products. TerraCycle assumes the shipping charges, made possible by partnerships with tobacco companies.

The arrangement — funded in large part by Portland businesses — has tremendous benefits, and it should spread to any other city without a plan in place to responsibly dispose of cigarette butts.

Not only have Portland’s buttlers diverted hundreds of thousands of cigarettes from the waste stream, the buttlers address some of the chief reasons that cause smokers to litter.

According to Keep America Beautiful, the cigarette littering rate in an area drops 9 percent for every new ash receptacle added. And since most smokers don’t carry pocket ashtrays with them, they blame the lack of receptacles for their littering.

Another reason many smokers drop their butts is that they consider it acceptable — even responsible — behavior, according to research on cigarette litter performed in Australia. If every other smoker they see is dropping cigarette butts on the ground or into gutters and storm drains to extinguish them, it follows suit that such behavior becomes acceptable.

But if enough bins are around and widely used, it becomes less common and less socially acceptable to litter cigarette butts. The result of this change in attitude is cleaner sidewalks, storm drains and waterways, which contributes to more appealing neighborhoods and less toxic water bodies.

Cutting back on cigarette litter requires behavior change among smokers. In Portland, cigarette buttlers are starting to cause that change.

The other big behavior change that must remain foremost in our minds? Getting smokers to kick the habit and keeping young people from ever taking it up.